select返回List

public interface EmployeeMapper {public List<Employee> getEmpsByLastNameLike(String lastName);}

    <!--    public List<Employee> getEmpsByLastNameLike(String lastName);--><!--resultType;如果返回的是一个集合，要写集合中元素的类型--><select id = "getEmpsByLastNameLike" resultType="com.atguigu.mybatis.bean.Employee">select * from tb1_employee where last_name like #{lastName}
</select>

   @Testpublic void test03() throws IOException {SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();SqlSession sqlSession = sqlSessionFactory.openSession();try{EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);List<Employee> like = mapper.getEmpsByLastNameLike("%e%");for (Employee employee : like){System.out.println(employee);}}finally {sqlSession.close();}}

select返回map

public interface EmployeeMapper {//返回一条记录的map；key就是列名，值就是对应的值public Map<String,Object> getEmpByIdReturnMap(Integer id);}

    <!--    public Map<String,Object> getEmpByIdReturnMap(Integer id);--><select id="getEmpByIdReturnMap" resultType="map">select * from tb1_employee where id = #{id}</select>

  @Testpublic void test03() throws IOException {SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();SqlSession sqlSession = sqlSessionFactory.openSession();try{EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);Map<String,Object> map = mapper.getEmpByIdReturnMap(1);System.out.println(map);}finally {sqlSession.close();}}

select返回多条记录封装的map

public interface EmployeeMapper {//多条记录封装一个map：Map<String, Employee>:键是这条记录的主键，值是这条记录的主键，值是记录封装后的javaBean//告诉mybatis封装这个map的时候，使用哪个属性作为map的key@MapKey("id")public Map<Integer,Employee> getEmpByLastNameLikeReturnMap(String lastName);}

    <!--resultType;如果返回的是一个集合，要写集合中元素的类型--><!--    public Map<Integer,Employee> getEmpByLastNameLikeReturnMap(String lastName);-->
<select id="getEmpByLastNameLikeReturnMap" resultType="com.atguigu.mybatis.bean.Employee">select * from tb1_employee where last_name like #{lastName}</select>

    @Testpublic void test03() throws IOException {SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();SqlSession sqlSession = sqlSessionFactory.openSession();try{EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);Map<Integer, Employee> map = mapper.getEmpByLastNameLikeReturnMap("%j%");System.out.println(map);}finally {sqlSession.close();}}